1. Field of the Invention
This invention relates to cap constructions for hand-held dispensers, and more particularly to dispensers of the type especially adapted to discharge controlled amounts of liquid over a predetermined area or line.
2. Description of the Related Art Including Information Disclosed Under 37 CFR .sctn..sctn.1.97-1.99
In the past there has been proposed a number of dispenser caps having a reduced diameter tip portion the end of which was intended to be severed, as by cutting or snipping with a scissors, to expose a discharge orifice of small dimension, whereby the contents could be dispensed by inverting it and applying the tip to an area to be treated. In some designs, the user was instructed to squeeze the dispenser in order to effect the discharge.
A number of problems with such prior dispensers have arisen.
Where the dispenser was being used to apply a substance to the scalp of a user, the sharp point of the cut tip often scratched or punctured the skin, causing pain and irritation, and possibly infection.
Also the user had difficulty in determining the proper position and angle of the cut. With tapered tips, cutting at one location would produce an orifice which was too large, and thus led to problems with control and with excessive flow of the liquid solution. On the other hand, if the tip were cut nearer its end, the resulting orifice might be too small, again leading to difficulty in establishing a comfortable flow rate which would lend itself to controlled application of the liquid by the user.
In other arrangements, the cutting procedure itself could cause difficulty, since a knife, razor or scissors was usually needed, and if the instrument was not especially sharp, the plastic of which the cap was constituted tended to resist being severed cleanly, leaving burrs, tears, or causing warping of the resultant opening.
A prior plastic dispenser of the type having a manual break-away tip which was employed as an ampul, is illustrated and described in U.S. Pat. No. 4,926,915, issued to H. Deussen, and entitled "AMPUL". Since this device was not intended for application of liquid to the skin or scalp, the possible existence of sharp edges at the break-away opening was generally not a consideration. However, the possibility of inadvertent breaking or opening of the ampul existed if it was dropped or handled roughly, and this constituted a distinct disadvantage and drawback.
In other caps, where a break-away tip was molded integrally with the remainder of the cap, there was of necessity a requirement to hold the tolerances closely, so that preferably the inner and outer surfaces of the tip, after cutting, were generally concentric. This requirement was difficult to achieve in practice, particularly where the dimensions were small, and where the required mold tolerances might be as stringent as a few thousandths of an inch or less.
Generally, prior manually openable break-away caps have not found widespread use because of the likelihood of damage to the seal and inadvertent discharge of the container contents as a result of dropping or rough handling.